U.S. patent number 10,770,696 [Application Number 15/950,617] was granted by the patent office on 2020-09-08 for top cover assembly of secondary battery and secondary battery.
This patent grant is currently assigned to CONTEMPORARY AMPEREX TECHNOLOGY CO., LIMITED. The grantee listed for this patent is CONTEMPORARY AMPEREX TECHNOLOGY CO., LIMITED. Invention is credited to Baisong Chen, Xiaobo Chen, Peng Wang, Zhiyu Wang, Kai Wu, Taosheng Zhu.
United States Patent |
10,770,696 |
Chen , et al. |
September 8, 2020 |
Top cover assembly of secondary battery and secondary battery
Abstract
Provided are a top cover assembly and a secondary battery
containing the same. The top cover assembly includes a first
electrode terminal, a conduction member, a second electrode
terminal, and a top cover plate insulated from the first electrode
terminal and electrically connected to the second electrode
terminal, the secondary battery further comprises a contact plate
which is attached to the top cover plate, the conduction member is
insulated from the top cover plate and comprises an electrode
terminal connection portion, a first fuse member, a contact plate
connection portion, and a connection layer, the first fuse member
has a melting point lower than the electrode terminal connection
portion and the contact plate connection portion; the first fuse
member is connected to the electrode terminal connection portion
via the connection layer, and/or the first fuse member is connected
to the contact plate connection portion via the connection
layer.
Inventors: |
Chen; Baisong (Ningde,
CN), Wang; Peng (Ningde, CN), Wu; Kai
(Ningde, CN), Wang; Zhiyu (Ningde, CN),
Chen; Xiaobo (Ningde, CN), Zhu; Taosheng (Ningde,
CN) |
Applicant: |
Name |
City |
State |
Country |
Type |
CONTEMPORARY AMPEREX TECHNOLOGY CO., LIMITED |
Ningde |
N/A |
CN |
|
|
Assignee: |
CONTEMPORARY AMPEREX TECHNOLOGY
CO., LIMITED (Ningde, CN)
|
Family
ID: |
1000005044332 |
Appl.
No.: |
15/950,617 |
Filed: |
April 11, 2018 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20190027717 A1 |
Jan 24, 2019 |
|
Foreign Application Priority Data
|
|
|
|
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Jul 20, 2017 [CN] |
|
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2017 1 0599686 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M
2/30 (20130101); H01M 2/348 (20130101); H01M
2/0473 (20130101); H01M 2/0486 (20130101); H01M
2/345 (20130101); H01M 2200/103 (20130101); H01M
2200/20 (20130101) |
Current International
Class: |
H01M
2/04 (20060101); H01M 2/30 (20060101); H01M
2/34 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Siddiquee; Muhammad S
Attorney, Agent or Firm: Tucker Ellis LLP
Claims
What is claimed is:
1. A top cover assembly of a secondary battery, comprising: a first
electrode terminal, a conduction member, a second electrode
terminal, and a top cover plate, wherein the top cover plate is
insulated from the first electrode terminal, and the top cover
plate is electrically connected to the second electrode terminal,
wherein the secondary battery further comprises a contact plate,
and the contact plate is attached to the top cover plate, and the
conduction member is insulated from the top cover plate, wherein
the conduction member comprises an electrode terminal connection
portion, a first fuse member, and a contact plate connection
portion, wherein the electrode terminal connection portion is
electrically connected to the first electrode terminal, the first
fuse member is electrically connected between the electrode
terminal connection portion and the contact plate connection
portion, and a melting point of the first fuse member is lower than
a melting point of the electrode terminal connection portion and a
melting point of the contact plate connection portion, wherein the
contact plate is configured to deform under an internal pressure of
the secondary battery and to be electrically connected to the
contact plate connection portion when the internal pressure of the
secondary battery exceeds a reference pressure, for forming an
electric connection path passing through the first electrode
terminal and the second electrode terminal, and wherein the
conduction member further comprises a connection layer, wherein the
first fuse member is electrically connected to the electrode
terminal connection portion via the connection layer, and the
connection layer is configured to enhance a connection strength
between the first fuse and the electrode terminal connection
portion; and/or the first fuse member is electrically connected to
the contact plate connection portion via the connection layer, and
the connection layer is configured to enhance a connection strength
between the first fuse and the contact plate connection
portion.
2. The top cover assembly according to claim 1, wherein the
electrode terminal connection portion and/or the contact plate
connection portion is made of a first metal material, the first
fuse member is made of a second metal material, and the connection
layer is made of a third metal material, wherein a bonding force
formed between the third metal material and the first metal
material and a bonding force formed between the third metal
material and the second metal material are both greater than a
bonding force formed between the first metal material and the
second metal material.
3. The top cover assembly according to claim 2, wherein the third
metal material is nickel, nickel alloy, tin, tin alloy, bismuth, or
bismuth alloy, the first metal material is aluminum or aluminum
alloy, the second metal material is a metal comprising one or more
elements selected from a group consisting of bismuth, tin, lead,
zinc, and indium.
4. The top cover assembly according to claim 1, wherein a number of
the connection layer is two, wherein one of the two connection
layers is connected to the electrode terminal connection portion,
the other one of the two connection layers is connected to the
first fuse member, and the two connection layers are welded to each
other.
5. The top cover assembly according to claim 1, further comprising
an insulation member, wherein the conduction member is insulated
from the top cover plate by the insulation member, and wherein a
first through hole is defined in the insulation member, and the
contact plate deformed contacts the contact plate connection
portion through the first through hole.
6. The top cover assembly according to claim 5, wherein the
insulation member comprises a first portion and a second portion
connected to the first portion, wherein the first portion is fixed
between the electrode terminal connection portion and the top cover
plate, and the second portion surrounds the contact plate
connection portion, wherein the first through hole is defined in
the second portion.
7. The top cover assembly according to claim 1, further comprising
a thermo-expandable portion made of an insulative and thermally
expandable material, wherein the first fuse member and the
thermo-expandable portion are arranged along a thickness direction
of the conduction member, the thermo-expandable portion is located
above the first fusing portion, and the thermo-expandable portion
is respectively laminated to the electrode terminal connection
portion and the contact plate connection portion.
8. The top cover assembly according to claim 7, further comprising
an insulation member, wherein the conduction member is insulated
from the top cover plate via the insulation member, and the
insulation member and the thermo-expandable portion are formed as
an integral structure.
9. A secondary battery comprising the top cover assembly according
to claim 1, a housing and an electrode assembly, wherein the top
cover assembly is connected to an opening of the housing and forms
a packaging space, wherein the electrode assembly comprises a first
electrode, a second electrode, and a separator interposed between
the first electrode and the second electrode, wherein the first
electrode terminal is electrically connected to the first
electrode, and the second electrode terminal is electrically
connected to the second electrode; and wherein the electrode
assembly is packaged in the packaging space.
10. The secondary battery according to claim 9, wherein the
secondary battery further comprises a second fuse member, and the
first electrode terminal is electrically connected to the first
electrode via the second fuse member, and/or the secondary battery
further comprises a third fuse member, and the second electrode
terminal is electrically connected to the second electrode via the
third fuse member.
11. The secondary battery according to claim 9, wherein the
electrode terminal connection portion and/or the contact plate
connection portion is made of a first metal material, the first
fuse member is made of a second metal material, and the connection
layer is made of a third metal material, wherein a bonding force
formed between the third metal material and the first metal
material and a bonding force formed between the third metal
material and the second metal material are both greater than a
bonding force formed between the first metal material and the
second metal material.
12. The secondary battery according to claim 11, wherein the third
metal material is nickel, nickel alloy, tin, tin alloy, bismuth, or
bismuth alloy, the first metal material is aluminum or aluminum
alloy, the second metal material is a metal comprising one or more
elements selected from a group consisting of bismuth, tin, lead,
zinc, and indium.
13. The secondary battery according to claim 9, wherein a number of
the connection layer is two, wherein one of the two connection
layers is connected to the electrode terminal connection portion,
the other one of the two connection layers is connected to the
first fuse member, and the two connection layers are welded to each
other.
14. The secondary battery according to claim 9, wherein the top
cover assembly further comprises an insulation member, wherein the
conduction member is insulated from the top cover plate by the
insulation member, and wherein a first through hole is defined in
the insulation member, and the contact plate deformed contacts the
contact plate connection portion through the first through
hole.
15. The secondary battery according to claim 14, wherein the
insulation member comprises a first portion and a second portion
connected to the first portion, wherein the first portion is fixed
between the electrode terminal connection portion and the top cover
plate, and the second portion surrounds the contact plate
connection portion, wherein the first through hole is defined in
the second portion.
16. The secondary battery according to claim 9, wherein the top
cover assembly further comprises a thermo-expandable portion made
of an insulative and thermally expandable material, wherein the
first fuse member and the thermo-expandable portion are arranged
along a thickness direction of the conduction member, the
thermo-expandable portion is located above the first fusing
portion, and the thermo-expandable portion is respectively
laminated to the electrode terminal connection portion and the
contact plate connection portion.
17. The secondary battery according to claim 16, wherein the top
cover assembly further comprises an insulation member, wherein the
conduction member is insulated from the top cover plate via the
insulation member, and the insulation member and the
thermo-expandable portion are formed as an integral structure.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority to Chinese Patent
Application No. 201710599686.4, filed on Jul. 20, 2017, the content
of which is incorporated herein by reference in its entirety.
TECHNICAL FIELD
The present application relates to the technical field of energy
storage devices and, particularly, relates to a top cover assembly
of a secondary battery and a secondary battery.
BACKGROUND
Power batteries (e.g., lithium-ion batteries), due to advantages of
high energy density, high power density, long cycling life, long
storage time, etc., are widely used in portable electronic devices
such as mobile phones, digital video cameras and portable
computers, and also have a wide application prospect in electric
transportation vehicles such as electric vehicles, electric
bicycles and so on, and large-and-medium-sized electric equipment
such as energy storage facilities and so on. The power batteries
have become a key to solving global problems such as energy crisis
and environmental pollution.
When the power battery is overcharged, decomposition of an
electrolyte solution in the power battery causes an internal
pressure of the power battery to increase, causing fire and
explosion to the battery. In order to prevent the fire and
explosion caused by an increase of the internal pressure, an
external short-circuit unit is generally used and a fuse is placed
between a positive electrode and a positive electrode terminal.
When the internal pressure of the power battery is increased, the
positive electrode and the negative electrode of an electrode
assembly are electrically connected into a short circuit by the
external short-circuit unit to form a large current which fuses the
fuse between the positive electrode and the positive electrode
terminal, thereby terminating the charging of the electrode
assembly.
However, the above structure reduces tolerance of the power battery
against high temperature environment. For example, the above
structure greatly increases the probability of thermal runaway of
the power battery in a hot-box test. The specific reasons are
described as follows. In the high temperature environment, not only
the internal pressure of the power battery increases with the
decomposition of the electrolyte solution at a high temperature,
but also an internal resistance of the electrode assembly
increases. In this case, if the positive electrode and the negative
electrode of the power battery are electrically connected into a
short circuit by the external short-circuit unit, the electrode
assembly generates more heat due to the increase of the internal
resistance and the short-circuit current, which increases the risk
of fire and explosion of the power battery. In other words, the
existing external short-circuit unit can only solve the overcharge
problem of the power battery under normal temperature conditions,
but increases the probability of thermal runaway under a high
temperature environment.
In order to reduce the probability of thermal runaway of a
secondary battery, the secondary battery in the related art further
includes a fuse member made of a low-melting-point alloy, and the
fuse member is connected to a negative conduction member to ensure
the fuse portion can be melted to cut off the short circuit during
the hot-box test. However, when the connection strength between the
fuse member and the negative conduction member is low, the contact
resistance between the fuse member and the negative conduction
member is relatively great, causing the fuse member to fuse when
the fuse portion is overcharged to form a short circuit at normal
temperature. As a result, even the overcharge problem of the power
battery under normal temperature conditions cannot be solved,
reducing the safety of the secondary battery.
SUMMARY
The present application provides a top cover assembly of a
secondary battery and a secondary battery, which can improve safety
performance of the secondary battery.
The first aspect of the present application provides a top cover
assembly of a secondary battery, including: a first electrode
terminal, a conduction member, a second electrode terminal, and a
top cover plate, wherein the top cover plate is insulated from the
first electrode terminal, and the top cover plate is electrically
connected to the second electrode terminal, wherein the secondary
battery further includes a contact plate, and the contact plate is
attached to the top cover plate, and the conduction member is
insulated from the top cover plate, wherein the conduction member
includes an electrode terminal connection portion, a first fuse
member, and a contact plate connection portion, wherein a melting
point of the first fuse member is lower than a melting point of the
electrode terminal connection portion and a melting point of the
contact plate connection portion, wherein the contact plate is
configured to deform under an internal pressure of the secondary
battery and to be electrically connected to the contact plate
connection portion when the internal pressure of the secondary
battery exceeds a reference pressure, for forming an electric
connection path passing through the first electrode terminal and
the second electrode terminal, and wherein the conduction member
further includes a connection layer, wherein the first fuse member
is connected to the electrode terminal connection portion via the
connection layer, and/or the first fuse member is connected to the
contact plate connection portion via the connection layer.
In an embodiment, the electrode terminal connection portion and/or
the contact plate connection portion is made of a first metal
material, the first fuse member is made of a second metal material,
and the connection layer is made of a third metal material, wherein
a bonding force formed between the third metal material and the
first metal material and a bonding force formed between the third
metal material and the second metal material are both greater than
a bonding force formed between the first metal material and the
second metal material.
In an embodiment, the third metal material is nickel, nickel alloy,
tin, tin alloy, bismuth, or bismuth alloy, the first metal material
is aluminum or aluminum alloy, the second metal material is a metal
including one or more elements selected from a group consisting of
bismuth, tin, lead, zinc, and indium.
In an embodiment, a number of the connection layer is two, wherein
one of the two connection layers is connected to the electrode
terminal connection portion, the other one of the two connection
layers is connected to the first fuse member, and the two
connection layers are welded to each other.
In an embodiment, the top cover assembly further includes an
insulation member, wherein the conduction member is insulated from
the top cover plate by the insulation member, and wherein a first
through hole is defined in the insulation member, and the contact
plate deformed contacts the contact plate connection portion
through the first through hole.
In an embodiment, the insulation member includes a first portion
and a second portion connected to the first portion, wherein the
first portion is fixed between the electrode terminal connection
portion and the top cover plate, and the second portion surrounds
the contact plate connection portion, wherein the first through
hole is defined in the second portion.
In an embodiment, the top cover assembly further includes a
thermo-expandable portion made of an insulative and thermally
expandable material, wherein the first fuse member and the
thermo-expandable portion are arranged along a thickness direction
of the conduction member, the thermo-expandable portion is located
above the first fusing portion, and the thermo-expandable portion
is respectively laminated to the electrode terminal connection
portion and the contact plate connection portion.
In an embodiment, the top cover assembly further includes an
insulation member, wherein the conduction member is insulated from
the top cover plate via the insulation member, and the insulation
member and the thermo-expandable portion are formed as an integral
structure.
A second aspect of the present application provides a secondary
battery. The secondary battery includes the top cover assembly in
any of the embodiments as described above, a housing, and an
electrode assembly, wherein the top cover assembly is connected to
an opening of the housing and forms a packaging space, wherein the
electrode assembly includes a first electrode, a second electrode,
and a separator interposed between the first electrode and the
second electrode, wherein the first electrode terminal is
electrically connected to the first electrode, and the second
electrode terminal is electrically connected to the second
electrode; and wherein the electrode assembly is packaged in the
packaging space.
In an embodiment, the secondary battery further includes a second
fuse member, and the first electrode terminal is electrically
connected to the first electrode via the second fuse member, and/or
the secondary battery further includes a third fuse member, and the
second electrode terminal is electrically connected to the second
electrode via the third fuse member.
The solutions provided by the present application at least have the
following beneficial effects:
The top cover assembly of a secondary battery provided in the
present application includes a conduction member, and the
conduction member includes an electrode terminal connection
portion, a first fuse member, and a contact plate connection
portion. The first fuse member has a melting point lower than the
electrode terminal connection portion and the contact plate
connection portion. In order to prevent the risk of virtual
connection between the first fuse member and the electrode terminal
connection portion and between the first fuse member and the
contact plate connection portion, the conduction member further
includes a connection layer which may be provided on at least one
of the electrode terminal connection portion and the contact plate
connection portion. The first fuse member 12b can be connected to
the electrode terminal connection portion via the connection layer,
or be connected to the contact plate connection portion via the
connection layer. Or a connection layer is respectively arranged on
the electrode terminal connection portion and the contact plate
connection portion, and the first fuse member is respectively
connected to the electrode terminal connection portion 12a and the
contact plate connection portion via the connection layer. The
connection layer serves to increase the connection strength of the
first fuse member with the electrode terminal connection portion
and the contact plate connection portion. On the one hand, in the
hot-box test, a current can be reliably transmitted among the
electrode terminal connection portion, the first fuse portion, and
the contact plate connection portion. When the temperature
increases due to the heat generated the current and reaches a value
at which the first fuse member fuses, the first fuse portion
reliably fuses. On the other hand, under normal temperature
conditions, when the secondary battery is in an overcharged state,
the contact plate deforms under an effect of the internal pressure
to be electrically connected to the contact plate connecting
portion. The arrangement of the connection layer can reduce the
contact resistance between the first fuse member and the electrode
terminal connection portion and between the first fuse member and
the contact plate connection portion, so that the first fuse member
will not fuse because of heat generated due to an excessive
resistance, thereby improving the safety of the secondary
battery.
It should be understood that the above general description and the
following detailed description are merely exemplary and are not
intended to limit the present application.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a cross-sectional view of a secondary battery provided in
an embodiment of the present application;
FIG. 2 is an exploded view of a top cover assembly of a secondary
battery provided in an embodiment of the present application;
FIG. 3 is a cross-sectional view of a top cover assembly of a
secondary battery provided in an embodiment of the present
application; and
FIG. 4 is an enlarged view of portion A in FIG. 3.
REFERENCE SIGNS
1--top cover assembly; 11--first electrode terminal; 11a--riveting
portion; 11b--flange portion; 12--conduction member; 12a--electrode
terminal connection portion; 12b--first fuse member; 12c--contact
plate connection portion; 13--second electrode terminal; 14--top
cover plate; 141--hole; 15--second electrode terminal conduction
member; 16--resistor; 2--electrode assembly; 3--housing;
4--insulation member; 41--first portion; 42--second portion;
421--through hole; 5--sealing member; 6--contact plate; 61--edge
portion; 62--deformable portion; 63--central portion;
7--thermo-expandable portion; 101--second fuse member; 102--third
fuse member; 104--first insulation member; 104a--air hole;
105--second insulation member; 106--explosion-proof valve;
107--protection patch for explosion-proof valve; 108--liquid
injection hole.
The accompanying drawings herein are incorporated into the
specification and constitute a part of the specification, which
show embodiments suitable for the present application, and are used
to explain the principle of the present application together with
the specification.
DESCRIPTION OF EMBODIMENTS
The present application will be further described in detail through
specific embodiment in combination with the appended drawings.
As shown in FIG. 1, the present application provides a top cover
assembly 1 of a secondary battery. The top cover assembly 1
includes a first electrode terminal 11, a conduction member 12, a
second electrode terminal 13, and a top cover plate 14. The first
electrode terminal 11 and the second electrode terminal 13 are used
for electrical connection to the electrode assembly 2, and are
installed to extend beyond the top cover plate 14, so that the
electrode assembly 2 can be electrically connected to a component
outside of a housing 3, thereby outputting electric energy in the
electrode assembly 2. The polarity of the first electrode terminal
11 and the polarity of the second electrode terminal 13 are not
limited in the present application. When the first electrode
terminal 11 is a positive electrode terminal, the second electrode
terminal 13 is a negative electrode terminal, and vice versa.
As shown in FIG. 2, each of the first electrode terminal 11 and the
second electrode terminal 13 includes a riveting portion 11a and a
flange portion 11b. When the top cover assembly 1 and the housing 3
are assembled together, the flange portion 11b is located inside of
the housing 3, the riveting portion 11a is located outside of the
housing 3, and the conduction member 12 is riveted to the riveting
portion 11a, so that the conduction member 12 is supported at a
first side (for example, an external side) of the top cover plate
14 from an exterior of the housing 3, the flange portion 11b is
supported at a second side (for example, an internal side) of the
top cover plate 14 from the interior of the housing 3, and the
first side and the second side are opposite to each other. As such,
the first electrode terminal 11 and the second electrode terminal
13 are fixed to the top cover plate 14.
It should be noted that the manner of connection between the
conduction member 12 and the first electrode terminal 11 is not
limited to riveting. For example, the riveting portion 11a may be
replaced by a screw, and the conduction member 12 and the first
electrode terminal 11 are in thread connection. Or, the conduction
member 12 may be welded to the first electrode terminal 11.
The conduction member 12 includes an electrode terminal connection
portion 12a, a first fuse member 12b, and a contact plate
connection portion 12c. The electrode terminal connection portion
12a is riveted to the riveting portion 11a, the first fuse member
12b and the contact plate connection portion 12c are suspended, and
the first fuse member 12b and the contact plate connection portion
12c are placed on a side of the electrode terminal connection
portion 12a close to the second electrode terminal 13.
As shown in FIGS. 3-4, the top cover plate 14 is electrically
connected to the second electrode terminal 13. The top cover plate
14 is respectively insulated from the first electrode terminal 11
and the conduction member 12. For example, the top cover assembly 1
further includes an insulation member 4 and a sealing member 5. The
insulation member 4 includes a first portion 41 and a second
portion 42, the first portion 41 is tightly clamped and fixed
between the top cover plate 14 and the conduction member 12, the
riveting portion 11a of the first electrode terminal 11 extends
through the first portion 41 and beyond the external side of the
top cover plate 14, and the second portion 42 surrounds a
peripheral edge of the contact plate connection portion 12c and a
peripheral edge of the first fuse member 12b. The sealing portion 5
is sleeved on an outside of a lower portion of the riveting portion
11a and is in contact with the insulation member 4. The insulating
portion 4 achieves insulation between the top cover plate 14 and
the first electrode terminal 11. The sealing member 5 realizes the
top cover plate 14 and the first electrode terminal 11 are
sealed.
The riveting portion 11a of the second electrode terminal 13 is
further connected with a second electrode terminal conduction
member 15, and the second electrode terminal 13 can be conveniently
and electrically connected to external components via the second
electrode terminal conduction member 15. A same sealing member as
the sealing member 5 on a side of the first electrode terminal 11
is placed on one side of the second electrode terminal 13, so as to
achieve sealing at the second electrode terminal 13. A resistor 16
is connected between the second electrode terminal conduction
member 15 and the top cover plate 14, to reduce the current in the
circuit. When a conductor penetrates through the housing 3 and
causes a short circuit in the secondary battery, the resistor 16
can reduce the short-circuit current, reduce the probability of
accidents such as fire. The resistor 16 is set based on the
secondary battery safety considerations.
Further referring to FIGS. 2-4, the secondary battery further
includes a contact plate 6 attached to the top cover plate 14. A
hole 141 is defined in the top cover plate 14. When the internal
pressure of the secondary battery exceeds a reference pressure, the
contact plate 6 deforms under the effect of internal pressure so
that the deformed contact plate 6 can contact the contact plate
connection portion 12c through the hole 141. At this time, the
first electrode terminal 11 and the second electrode terminal 13
are electrically connected to each other, and the short circuit
state of the secondary battery is maintained.
A through hole 421 is defined in a part of the second portion 42
directly facing the contact plate 6 so that the deformed contact
plate 6 contacts the contact plate connection portion 12c through
the through hole 421.
The contact plate 6 includes an edge portion 61, a deformable
portion 62 and a central portion 63. The deformable portion 62
connects the edge portion 61 and the central portion 63, and the
edge portion 61 is attached to the top cover plate 14. After the
contact plate 6 deforms, the central portion 63 contacts the
contact plate connection portion 12c and the deformable portion 62
is bent to protrude along a direction away from the top cover plate
14.
Different portions of the contact plate 6 may have different
thicknesses, and the portion having a different thicknesses from
the other portions may be a protrusion of a portion of the contact
plate 6 contacting with the contact plate connection portion 12c,
or the thickness of the contact plate 6 may gradually change from a
peripheral area toward a central area of the contact plate 6, and
the thickness of the central area is greatest so that the contact
piece 6 can contact the contact plate connection portion 12c when
the contact plate 6 deforms.
The first fuse member 12b can fuse at a predetermined temperature,
and a melting point of the first fuse member 12b is lower than the
electrode terminal connection portion 12a and the contact plate
connection portion 12c. In order to ensure the reliability of the
connection between the first fuse member 12b and the electrode
terminal connection portion 12a and between the first fuse member
12b and the contact plate connection portion 12c, the conduction
member 12 further includes a connection layer (not shown in the
drawings) which may be provided on at least one of the electrode
terminal connection portion 12a and the contact plate connection
portion 12c, so that the first fuse member can function in the hot
box test. Correspondingly, the first fuse member 12b may be
connected to the electrode terminal connection portion 12a via the
connection layer, or be connected to the contact plate connection
portion 12c via the connection layer. Or a connection layer may be
respectively arranged on the electrode terminal connection portion
12a and the contact plate connection portion 12c, and the first
fuse member 12b is respectively connected to the electrode terminal
connection portion 12a and the contact plate connection portion 12c
via the connection layer.
In the above description, the connection layer may serve to
increase the connection strength of the first fuse member 12b with
the electrode terminal connection portion 12a and the contact plate
connection portion 12c. On the one hand, in the hot-box test, a
current can be reliably transmitted among the electrode terminal
connection portion 12a, the first fuse member 12b, and the contact
plate connection portion 12c. When the temperature increases due to
the heat generated by the current and reaches a value at which the
first fuse member 12b fuses, the first fuse member 12b reliably
fuses. On the other hand, under normal temperature conditions, when
the secondary battery is in an overcharged state, the contact plate
deforms under an effect of the internal pressure to be electrically
connected to the contact plate connecting portion. The arrangement
of the connection layer can reduce the contact resistance between
the first fuse member 12b and the electrode terminal connection
portion 12a and between the first fuse member 12b and the contact
plate connection portion 12c, so that the first fuse member 12b
will not fuse because of heat generated due to an excessive
resistance, thereby improving the safety of the secondary
battery.
According to one embodiment, at least one of the electrode terminal
connection portion 12a and the contact plate connection portion 12c
is made of a first metal material, the first fuse member 12b is
made of a second metal material, and the connection layer is made
of a third metal material. In order to increase the connection
strength, it may be set that a bonding force between the third
metal material and the first metal material and the bonding force
between the third metal material and the second metal material are
both greater than the bonding force between the first metal
material and the second metal material. Different metal materials
have different bonding abilities during cold bonding or thermal
bonding. In this solution, the connection layer is set by using the
inherent properties of the metal material so that the first fuse
member 12b is respectively bonded firmly to the electrode terminal
connection portion 12a and the contact plate connection portion
12c, so as to improve the reliability of connection between the
first fuse member 12b and the conduction member 12.
Optionally, the third metal material may be nickel, nickel alloy,
tin, tin alloy, bismuth, or bismuth alloy, etc. The first metal
material may be aluminum or aluminum alloy. The second metal
material may be selected from a group combinations of bismuth, tin,
lead, zinc, indium, and combinations thereof. The above-mentioned
metal material has good weldability, and during welding, the
above-mentioned metal materials have higher degree of bonding and a
better bonding firmness.
The first metal material, the second metal material, and the third
metal material are not limited to those described above, and in
other embodiments, the first metal material, the second metal
material, and the third metal material may have other different
options.
It should be noted that the connection layer may be a solid
component, or as a plating layer formed on a solid component, which
is not limited in the present application. In an embodiment, the
connection layer may be formed by plating. In this case, the number
of the connection layer may be two, one of which is plated on the
electrode terminal connection portion 12a and the other is plated
on the first fuse member 12b, and the two connection layers are
bonded by welding. The connection layer formed by plating can
reduce the occupancy of the space and is beneficial to the
structural compactness of the top cover assembly 1. Meanwhile, such
a plating method can reduce connection of other manners, thereby
reducing the risk of connection failure.
In one embodiment, the top cover assembly 1 further includes a
thermo-expandable portion 7 made of an insulative and thermally
expandable material. As shown in FIG. 4, the first fuse member 12b
and the thermo-expandable portion 7 are placed along a thickness
direction of the conduction member 12. The thermo-expandable
portion 7 is located above the first fusing member 12b, and the
thermo-expandable portion 7 is respectively laminated onto the
electrode terminal connection portion 12a and the contact plate
connection portion 12c. When heated, the thermo-expandable portion
7 expands and deforms, and the contact plate connection portion 12c
is displaced away from the electrode terminal connection portion
12a under the expansion force of the thermo-expandable portion 7.
At this time, a gap is formed between the electrode terminal
connection portion 12a and the contact plate connection portion
12c, and the gap may provide a flow path for the fused first fuse
member 12b so that the melted first fuse member 12b flows out along
the flow path, thereby achieving the reliable disconnection of the
electric connection circuit between the electrode terminal
connection portion 12a and the contact plate connection portion
12c.
The thermo-expandable portion 7 may be made of a plastic material,
and the thermo-expandable portion 7 and the insulation member 4 may
be further integrated into an integral structure. Or, the thermal
expansion portion 7 may be separately made of a plastic
material.
The present application further provides a secondary battery, which
includes the top cover assembly 1 of a secondary battery as
described in any embodiment above, an electrode assembly 2 and a
housing 3. The top cover assembly 1 is connected to the opening of
the housing 3 and forms a packaging space, and the electrode
assembly 2 is packaged in the packaging space.
The electrode assembly 2 includes a first electrode, a second
electrode, and a separator placed between the first electrode and
the second electrode. The flange portion 11b of the first electrode
terminal 11 is electrically connected to the first electrode. The
flange portion 11b of the second electrode terminal 13 is
electrically connected to the second electrode.
The electrode assembly 2 is formed by helically winding the first
electrode together with the second electrode having an opposite
polarity to the first electrode and the separator. The separator is
an insulator interposed between the first electrode and the second
electrode. Or, the electrode assembly 2 may be formed by stacking a
plurality of first electrodes, a plurality of separators, and a
plurality of second electrodes, and the first electrodes,
separators and second electrodes are shaped like a plate or a
sheet.
The first electrode can be a negative electrode, and the second
electrode is a positive electrode. Or the first electrode can be a
positive electrode, and the second electrode is a negative
electrode.
The first electrode and the second electrode each have a thin plate
serving as a current collector. The thin plate of the first
electrode includes a first coating portion coated with an active
material and a first electrode tab uncoated with any active
material. The thin plate of the second electrode includes a second
coated portion coated with an active material and a second
electrode tab uncoated with any active material.
The housing 3 is formed to have a substantially cubic shape to form
a cavity for accommodating the electrode assembly 2 therein, and an
opening is formed at a side of the housing 3.
In order to avoid fire caused by overcharging, the secondary
battery further includes a second fuse member 101. The second fuse
member 101 is connected between the first electrode terminal 11 and
the first electrode. The second fuse member 101 may be made of a
material having a low melting point or the second fuse member 101
may have relatively a small flow area so that the second fuse
member 101 can quickly fuse under a great current, thereby
effectively avoiding overcharging.
Similarly, the secondary battery may further includes a third fuse
member 102 connected between the second electrode terminal 13 and
the second electrode, and the third fuse member 102 has the same
function as the second fuse member 101, which is not repeated
herein.
In addition, a first insulation member 104 and a second insulation
member 105 are further placed between the top cover plate 14 and
the electrode assembly 2. The first insulation member 104 is used
to insulate the top cover plate 14 from the first electrode tab,
and the second insulation member 105 is used to insulate the top
cover plate 14 from the second electrode tab.
An air hole 104a is defined in the first insulation member 104. The
gas decomposed from the electrode assembly exerts a pressure to the
contact plate 6 through the air hole 104a to deform the contact
plate 6.
The secondary battery further includes an explosion-proof valve
106, a protection patch 107 used for protecting the explosion-proof
valve 106, a liquid injection hole 108, and a sealing element used
for sealing the liquid injection hole 108, etc. The explosion-proof
valve 106 is configured to be turned on when the internal pressure
of the secondary battery reaches a predetermined pressure which may
be higher than a threshold pressure under which the contact plate 6
begins to deform.
The foregoing descriptions are merely embodiments of the present
application and are not intended to limit the present application.
For those skilled in the art, the present application may have
various modifications and changes. Any amendments, equivalent
substitution and improvement made within the principle of the
present application should be included in the protection scope of
the present application.
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